This proposal seeks continuation funding for the Population Database of the United States in 1880. Over the past three years, the Minnesota Population Center has cleaned, edited, and coded records describing basic demographic characteristics of all fifty million Americans enumerated by the Census of 1880. Although this database covers the entire 1880 population, it does not include all census variables. To exploit the research potential of these data, we now propose two improvements to the database: 1. We will add the missing information on health, education, employment, non-family relationships, and nuptiality to a ten-percent sample of the 1880 non-Hispanic white population and a twenty-percent sample of households containing blacks, American Indians, Chinese, and Hispanics. The completed sample will provide information for 5.7 million persons. With the rapid decline in data storage and processing costs during the past decade, scholars are increasingly capitalizing on the power of large census samples. A ten percent sample including all the information collected by the 1880 population census will provide a baseline for large-scale analysis of demographic change. The health information contained in the 1880 census is especially valuable, since it provides the earliest detailed nationally representative account of morbidity available for any country. These data will provide unparalleled insight into morbidity at the beginning of a key epidemiological transition. They will allow researchers to gauge the impact of long-run changes in public health measures and medical technology and to assess the impact of environmental factors on health in the absence of effective medical treatment. 2. We will take advantage of new record-linkage and data-mining technology to create linked representative samples of individuals and family groups from the censuses of 1860, 1870, 1900, and 1910 to the 1880 census. These representative linked samples will provide unprecedented opportunities for researchers to carry out individual-level analyses of social and geographic mobility and family transitions in the early stages of industrial development. [unreadable] [unreadable]